June 2013World Premiere!
Metrum Octave mkiiUpdated Octave NOS DAC Including USB Input Option
Will this DAC be as highly acclaimed as its predecessor?Review By Clive Meakins

Anyone
interested in DACs will surely know of the original Metrum Octave DAC released
in 2011. This was a non-oversampling (NOS) two-box DAC which made a big impact
on the market. Metrum have now released the Octave mkII; the core of the DAC is
much the same as the original. There are still four industrial DAC chips per
channel, whose identity is a fiercely guarded secret. There is still a direct
connection to the output RCAs, there being no OpAmps to cloud or tailor the
sound. The inputs include S/PDIF coax and optical and crucially there is now the
option to specify a USB input based on the M2Tech USB-to-I2S module. As I'm
wedded to computer-based digital music nowadays the addition of the USB option
is an important addition which obviates the need for an external USB-to-S/PDIF
converter. The Octave mkII with USB is priced at $1395 in the US and in Europe
it is €1075 inclusive of a painful but unavoidable 21% VAT. Without USB the
DAC costs $1230 or €950. The Octave mkII is available with front plate in
either silver or black.

Metrum also make the lower cost Quad and the HEX which is 2.5
times the price of the Octave; the number of DAC chips in each is denoted by the
product naming. The Octave mkII uses some of the upgrades developed for the HEX.
The USB input was one of these developments though whereas the HEX powers the
USB board internally, the Octave powers this board from your computer's USB
port. Cees Ruijtenberg is the designer and here's what he told me about the power
supply for the USB board; "Here we have used
the raw power coming from the USB socket to create a new and very clean voltage.
At the right side of the USB board you will see 4 capacitors which are a part of
a huge filter. This filter is working as a low pass filter having a -3dB point
at 15 Hz and -80dB at 10 kHz. From there a new voltage is generated by a
regulator circuit below the USB board which is giving a clean voltage to the USB
board. When looking at the noise the result is quite the same as in the case of
the Hex approach. This part of the electronics is still separated from the DAC
so there is no electric connection. To get the data from the USB part the data
is sent to very fast (50 MHz) opto couplers as used in data transmission
systems. This approach gives us full galvanic isolation and clean digital data."

Aside from the above changes the Octave now houses the DAC
power supply in the main chassis so the DAC is now a single chassis unit. The
mkII also now provides for 192kHz playback on S/PDIF and USB inputs, the final
change is an increase in the depth of the input buffer which should result in
reduced differences being heard between digital transports.

NOS is all very interesting but what about the sound?

Due to my computer setup needing a USB DAC I never got to hear
the original Octave so when the offer to review the mkII arrived I leapt at the
opportunity. The editor will tell you that he'd barely pressed "send" to email
the offer to me when my affirmative reply hit his screen. The DAC actually came
from the US to my home in the UK, it was a rather roundabout route as Metrums
are built in the Netherlands. The reason for United States sourcing of the DAC is that it
came from Fred Crane of StereoDesk
who handles North America Metrum sales; the speed of shipping was impressive as
the DAC arrived in only two days.

DAC reviews can be hard to write at times as many DACs are
more similar sounding than they are different so getting at their unique
characteristics can be challenging and time consuming. Refreshingly with the
Metrum Octave mkII we have a DAC endowed with characteristics which stand out
from most DACs. My initial reaction to the DAC was is one of very clear vocals,
great space around instruments and sounds standing out extremely well within the
soundstage. The DAC I'm told had only been run for a few hours before I received
it and as the Metrum NOS DACs have a reputation for needing considerable burn-in
I then fed it a diet of music all day for several days. As burn-in progressed I
noticed the sound smoothed out though it was never remotely harsh, mid-burn-in I
noted some mid-range leanness which was later eradicated.

Before going into details about the sound of the Octave mkII
there are some aspects I found useful to extract the best from this DAC. These
are a couple of tweaks which worked for me in my system. Feel free to try them
or ignore them.

USB Driver (Windows)

The USB input being M2Tech based uses the HiFace driver as
standard; this is supplied on a CD with the DAC. This driver is perfectly fine
and it's simple to install. I know from previous M2Tech experience that the
M2Tech driver for their Young DAC stood a chance of sounding just a touch
better. I also know that installing this driver can be a pain as it's expecting
to mate with the Young DAC. If you want to try this driver I have created some
instructions. If you have
problems please do not trouble Metrum or StereoDesk as they are not there to
provide software support for a driver they do not support.

With other DACs I've found the Young driver gave a richer
sound, with the Octave mkII this wasn't the case, possibly due to its deeper
input buffer. What did improve was the sound stage which became a little more
spacious.

Firmly Planted

IIt took me a while to spot this and I'm so glad I did. As my
computer running Jplay resides on a wooden shelf
and I find that short USB cables sound best, I just placed the Octave down on
the shelf next to the computer. When I compared the Octave to another DAC I
found the bass a little bloated. Hmm…shame I thought. I then wanted to try
some other interconnects which are very inflexible so I had to move the computer
and DAC. The DAC at this point ended up sitting on my solid floor. The bass
immediately tightened up and became highly textured. You don't have to place the
DAC on a solid floor but please to use it on a decent hi-fi rack.

Time For Serious Listening

With the Octave mkII well burnt-in I played a lot of music and
made notes for this review so here are some thoughts as they developed as
immediate reactions to what I heard. My system comprises Computer Audio using
Jplay, 2 record decks (Garrard 301 and Trans-Fi Salvation), preamp was the AVC-1
by John Chapman, a selection of power amplifiers; 300B SE, T-amps / chip-amps
and Valvet Er1 SE solidstate power amps feeding Open Baffle speakers (hybrid
Bastanis / Trans-Fi), there's DSP correction on the bass with 2 x 15 inch bass
drivers per channel being actively driven courtesy of XTZ amplification. Using a
two computer (streamer/audio) setup with Jplay here are some examples of what I
heard with a few tracks:

Jennifer Warnes Famous Blue Raincoat
"Bird on A Wire" –
some NOS DACs suffer at frequency extremes; any deficiencies should be obvious
with this track. What I heard is that Octave mkII has better vocal focus &
more bass impact than I was used to. Treble is well balanced, it's not
over-sparkly and is sweet. Instruments and vocals have greater presence than is
typical, there being more space around them and they have excellent depth.

Mary Chapin Carpenter Hometown Girl "Hometown Girl" – I
noticed that the DAC doesn't over-emphasize leading edges and decays are well
reproduced. There's great musical flow & expression without forced
aggression. Bass guitar notes somehow sound "deliberate" or purposeful. When the
there is a pumping rhythm it pumps for sure but only when the music intends
this.

George Martin In my Life "Golden Slumbers"
Phil Collins
– this track has tremendous drums in the middle which are totally thunderous
with the Octave.

Genesis Live "Watcher of the Skies" - Power and space,
this sounds track better than it has any right to.

The Who Who's Next "Behind Blue Eyes" – Vocal focus was
excellent and frankly hard to improve on. With Octave the steel guitar strings
sound like steel and the instruments have lots of space around them. Certainly
the depth with the Octave is greater than most DACs I've used; it's more of a
vinyl-like front-to-back depth.

The Rolling Stones Forty Licks "Brown Sugar" – This is not
the greatest recording but the Octave allows it to breath, it almost feels like
a live performance.

The Rolling Stones Forty Licks "She's Like a
Rainbow", "Paint
it Black", and "Satisfaction" – These are all vintage sounds but all the better for
it; they sounded really great, plenty of energy and atmosphere. Hardly precise
sounding in the way many modern recordings are but these vintage sounds came
across wonderfully. Vibrant.

Ben Harper Welcome to the Cruel World
"Whipping Boy" –
This is really well recorded but with bass that can be hard to resolve with
detail texture. No such problems here. It's easy to hear both drums and bass
guitar and importantly the interplay between them. A fabulous demo track.

Sonny Rollins Saxophone Colossus "Moritat" – Sonny's sax
comes over with a wonderful tone and realism, add to this the quality of the
double bass… I love it! I want to mention here that I've had great jazz
discussions with the supplier of the Octave, Fred Crane of StereoDesk; he has a
tremendous heritage with jazz that clearly helps him select great products to
offer his customers. He really knows about musical reproduction and what makes
it emotional.

Diana Krall Girl in The Other Room "Love me like a Man"
– Wow…Diana's vocals, the double bass, piano and drums; sublime. I play this
a lot on vinyl, I've not heard it anywhere near this good previously and this is
in comparison with a Garrard 301 deck and London Reference cartridge. Note to
self – buy Keith Jarrett's Koln Concert on CD, given the piano performance I
hear on this Krall track the Koln Concert will be totally stunning.

To try out the S/PDIF coax input I used OPPO BDP-103 and
BDP-105 for playing my ripped CDs. The sound of the OPPOs with their internal
DACs was more forward in presentation than the Octave and aggressive too. Some
of this character remained with the Octave acting as the DAC so the OPPO
transport was adding its own character to the sound I was hearing. Clearly the
S/PDIF input on the Octave works as you'd expect, the more pushy sound due to
using the OPPO isn't for me. With coax, optical and USB inputs on the Octave you
have plenty of options to find your preferred transport.

USB Power

Cees has done a tremendous job refining the computer USB power
line to run the USB converter board, these boards are very sensitive to power
quality; this becomes especially apparent when feeding a very high quality DAC
such as the Octave mkII. My inquisitive nature demanded I try something here; as
I had a suitable power supply on hand which could supply a less polluted 5V than
my computer USB, I had to try it. This is the $199 iFi
iUSBPower;
reviewed last month. What happens here is that the USB data feed from the
computer is used as normal but the 5V power now comes from the iUSBPower. The
in-built power supply filtering Cees provides then gets an even better start
taking a more pure 5V feed.

Powering the USB board from a separate supply opens up a
second option which I find brings benefits. I'm not a fan of hyper-expensive USB
cables; what I find works well are short USB cables and where possible splitting
the power wires from the data cables. You still need the ground wire to
accompany the data cables but removing the +5V wire from the USB cable I find
provides a performance lift. Initially I used an ISOLATE
cable from Australia based Elijah Audio
feeding into the iUSBPower, data and power are then fed from the iUSBPower via a
standard USB cable. Elijah Audio cables include Peter Belt treatments in their
manufacture.

The effect of the power tweak was certainly audible in my
system, there wasn't a night and day improvement due to the well-designed power
supply treatment Cees implemented but bass was deeper and tighter, the space
around instruments became a little larger and even better defined. I would
also describe the sound as being more composed too. When I've heard the
difference iUSBPower makes powering an entire USB DAC the improvement has been
more significant. Of course your computer is bound to have a different USB noise
signature compared to mine so I can't begin to know what benefit or otherwise
you may find.

The ISOLATE cable worked well enough for me to ask Michael at
the Elijah Audio to make me the next cable I wanted to try based on his ISOLAATE
BL cable but with a longer power cable (50cm); these cables cost $155 to
$200 depending on the length you select. This is a twin-headed USB cable; one
head comprises a USB Type A plug with data and ground wires, this plugs in to
the computer; the other head is a USB Type A plug with ground and +5V wires,
this plugs into the iUSBPower. Both sets of wires then meet at the USB Type B
plug which connects to the DAC. We now have the +5V separate from USB data wires
until they meet momentarily in the USB plug and socket. The big question is
would this segregation of data and power bring additional benefits. If it did
this might due to the power wires not now being able to mess with the impedance
of the cable, which should be 90 ohms; this is one explanation I've seen for
such effects.

The ISOLAATE BL cable configuration built on the ISOLATE +
standard USB cable benefits. The first improvement I noticed with that the sound
was yet more "composed", the music was even more at ease and more natural. How
can I better explain this? I'll have to use an automotive parallel; the more
composed sound I'm talking about is as if I'd swapped from a car with a highly
tuned but smallish capacity engine to a car with a big torquey V8. I also found
was even better stage depth and separation of instruments. Treble, as in
hi-hats, was better defined and more real sounding. As you might imagine I was
swapping between configurations listening to a piece of music for about 3
minutes at a time until I noticed with the ISOLAATE BL I'd reached the end of a
7 minute track. This says it all; it's a very worthwhile improvement.

If pushed I would say the ISOLATE + standard USB cable and iFi
IUSBPower gives 60% of the improvement of the ISOLAATE BL twin-headed cable +
iFiiUSBPower. The twin-headed solution is the one I'm now living with.

ISOLAATE BL is functionally close to the Gemini cable iFi have
designed for the iUSBPower, whether these two cables have an identical effect on
sound quality I cannot say as the Gemini wasn't available during my auditioning.

Conclusions

The Octave mkII has a mid-range which is very spacious and
natural with realism being especially strong due to image depth and impressive
tonality. Treatment of overly sibilant recordings is amongst the best I've
heard.

You must ensure the Octave mkII sits on a suitable rack if you
are to hear the DAC close to its best. With this optimized there's a lot of bass
drive, I find I'm drawn more strongly to the bass line and rhythm than is
normally the case, pacing is dictated by the music; depending on the music it
can be very infectious, it makes me move to the music. The bass does not
dominate but the Octave does ever so slightly highlight the bass. Is this 100%
neutral? Possibly not but I don't know many people who would complain about
this, most will welcome it.

A tweak I recommend for USB users; get yourself an iFi
iUSBPower with a twin-headed cable, you won't look back. Just do it. While you're
at it give installing the Young driver a try, you may just like it and what's
more it's free.

Even without the power tweaks I find the sound of the Octave
is particularly natural; it gels with the sound of my record decks which from me
is a huge compliment. It is not at all "in your face, aren't I impressive?"
sounding. It is an affair of the heart, not the head. In some ways the Octave
mkII mid-range reminds me of single-ended amplifiers, ones which are especially
lucid with vocals and instruments such as saxophone.

Given that I run two record decks and the music that moves me
the most I have on vinyl, how I can justify the purchase of the Octave mkII?
Instead of buying so much vinyl in future I can buy lower cost CDs and there's a
lot of very affordable second-hand CDs out there. With the Metrum Octave
mkII I can achieve a sound equivalent to vinyl and I can throw fabulous hi-res
digital into the mix too. The Octave mkII will be a great investment as it will
save me money on my music purchases. Or will it? I've just worked out that I'm
going to be buying a whole lot more music.

There
can be no doubt that the Metrum Octave mkII is a superb DAC by almost any
measure; it will suit those who prioritize natural and realistic presentation
over a hyper-analytical sound.